Exhaust system

Abstract

To provide an exhaust system capable of suppressing discharge of hydrocarbon immediately after start of an engine.SOLUTION: An exhaust system 1 includes: a catalytic converter 2 connected to an engine 101; an exhaust pipe 3 connected to a downstream side of the catalytic converter 2, the exhaust pipe 3 branched into a first exhaust pipe 31 and a second exhaust pipe 32 in the middle; a plasma reactor 5 interposed in the middle of the first exhaust pipe 3; an adsorption member 4 interposed in the middle of the first exhaust pipe 31, disposed between the catalytic converter 2 and the plasma reactor 5 and capable of adsorbing hydrocarbon in exhaust gas; and a valve 6 for adjusting balance between the amount of exhaust gas passing through the first exhaust pipe 31 and the amount of exhaust gas passing through the second exhaust pipe 32.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an exhaust system. [Background technology]

[0002] Conventionally, exhaust gas purification devices equipped with plasma reactors are known as devices that decompose harmful components such as hydrocarbons (HC) contained in exhaust gas (see, for example, Patent Document 1).

[0003] In this exhaust gas purification system, a bypass channel is provided upstream of the exhaust gas purification catalyst, bypassing the main channel, and a plasma reactor containing an HC adsorption catalyst is positioned in this bypass channel.

[0004] Furthermore, in this exhaust gas purification system, when the exhaust gas purification catalyst is not sufficiently active, the exhaust gas is diverted to a bypass channel where hydrocarbons are adsorbed by an HC adsorption catalyst, and a plasma reactor assists in the purification of hydrocarbons. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2005-90400 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, in exhaust gas purification devices such as those described in Patent Document 1, when exhaust gas is flowed through a bypass channel, the HC adsorption catalyst is located upstream of the exhaust gas purification catalyst. Therefore, there is a possibility that the temperature of the HC adsorption catalyst will rise while the temperature of the exhaust gas purification catalyst is low.

[0007] Therefore, if the exhaust gas purification catalyst is not sufficiently active, the temperature of the HC adsorption catalyst may rise, potentially causing the hydrocarbons adsorbed on the HC adsorption catalyst to desorb.

[0008] In that case, the hydrocarbons in the exhaust and the hydrocarbons desorbed from the HC adsorption catalyst would be treated solely by the plasma reactor, making it difficult to suppress hydrocarbon emissions.

[0009] Therefore, the object of the present invention is to provide an exhaust system that can suppress the emission of hydrocarbons immediately after engine startup. [Means for solving the problem]

[0010] The present invention [1] includes an exhaust system comprising: a catalytic converter connected to an engine; an exhaust pipe connected downstream of the catalytic converter, which branches into a first exhaust pipe and a second exhaust pipe; a plasma reactor interposed in the first exhaust pipe; an adsorption member interposed in the first exhaust pipe and positioned between the catalytic converter and the plasma reactor, capable of adsorbing hydrocarbons in the exhaust gas; and a valve for adjusting the balance between the amount of exhaust gas passing through the first exhaust pipe and the amount of exhaust gas passing through the second exhaust pipe.

[0011] With this configuration, until the catalyst in the catalytic converter is activated, the exhaust gas that has passed through the catalytic converter is passed through the first exhaust pipe, and hydrocarbons in the exhaust gas can be treated by the adsorption material and the plasma reactor.

[0012] In this process, the exhaust gas from the engine passes through the catalytic converter, adsorption material, and plasma reactor in that order.

[0013] Therefore, the temperature of the catalytic converter can be raised faster than that of the adsorbent material. As a result, the catalyst in the catalytic converter can be activated before the hydrocarbons adsorbed on the adsorbent material are detached from the adsorbent material.

[0014] After the catalyst in the catalytic converter is activated, hydrocarbons in the exhaust gas can be processed by the catalytic converter while hydrocarbons desorbed from the adsorbent material can be processed by the plasma reactor.

[0015] As a result, it is possible to suppress the hydrocarbon emissions immediately after engine startup.

[0016] The present invention [2] further includes a control device, and when the temperature inside the catalytic converter is lower than a first temperature at which the catalyst inside the catalytic converter is activated, the control device controls the valve so that all of the exhaust gas passes through the first exhaust pipe. The exhaust system of [1] above.

[0017] According to such a configuration, until the catalyst inside the catalytic converter is activated, hydrocarbons can be processed by the adsorption member and the plasma reactor.

[0018] Therefore, it is possible to suppress the emission of hydrocarbons until the catalyst inside the catalytic converter is activated.

[0019] The present invention [3] includes the exhaust system of [2] above, in which when the temperature inside the catalytic converter is equal to or higher than the first temperature and the temperature of the adsorption member is lower than a second temperature at which hydrocarbons desorb from the adsorption member, the control device controls the valve so that the amount of exhaust gas passing through the first exhaust pipe is not more than a predetermined amount.

[0020] According to such a configuration, when the temperature inside the catalytic converter becomes equal to or higher than the first temperature, the activated catalyst inside the catalytic converter can decompose the hydrocarbons in the exhaust gas.

[0021] Therefore, the valve is controlled so that, among the exhaust gas that has passed through the catalytic converter, not more than a predetermined amount flows through the first exhaust pipe, and the amount exceeding the predetermined amount flows through the second exhaust pipe.

[0022] Thereby, while raising the temperature of the adsorption member, the exhaust gas can be efficiently discharged outside the vehicle using the second exhaust pipe.

Effects of the Invention

[0023] According to the exhaust system of the present invention, the amount of hydrocarbon emissions immediately after engine startup can be suppressed. [Brief explanation of the drawing]

[0024] [Figure 1] Figure 1 is a schematic diagram of a vehicle equipped with one embodiment of the exhaust system of the present invention. [Figure 2] Figure 2 is a flowchart illustrating the control of the exhaust system shown in Figure 1. [Modes for carrying out the invention]

[0025] 1. Exhaust system configuration As shown in Figure 1, the exhaust system 1 is mounted on, for example, a vehicle 100.

[0026] The vehicle 100 includes an engine 101, an electrical system including a battery 102, an intake system (not shown) for drawing air into the engine 101, a fuel injection system (not shown) for supplying fuel to the engine 101, and an exhaust system 1 for exhausting air from the engine 101.

[0027] The exhaust system 1 comprises a catalytic converter 2, an exhaust pipe 3, an adsorption member 4, a plasma reactor 5, a valve 6, a power supply unit 7, a control unit 8, a first temperature sensor 9, a second temperature sensor 10, and an airflow meter 11.

[0028] (1) Catalytic converter The catalytic converter 2 is connected to the engine 101. Specifically, the catalytic converter 2 is a three-way catalytic converter that has a three-way catalytic converter as an example of a catalytic converter. The catalytic converter 2 uses its internal catalytic converter to decompose harmful components (hydrocarbons (HC), nitrogen oxides (NOx), and carbon monoxide (CO)) contained in the exhaust gas.

[0029] (2) Exhaust pipe The exhaust pipe 3 is connected to the catalytic converter 2. The exhaust pipe 3 is connected downstream of the catalytic converter 2 in the direction of exhaust gas flow. The exhaust gas discharged from the engine 101 and passing through the catalytic converter 2 is discharged outside the vehicle through the exhaust pipe 3. The exhaust pipe 3 branches into a first exhaust pipe 31 and a second exhaust pipe 32 along its course. In other words, the exhaust pipe 3 has a first exhaust pipe 31 and a second exhaust pipe 32.

[0030] The first exhaust pipe 31 is a pipe for guiding exhaust gas to the adsorption member 4 and the plasma reactor 5. The adsorption member 4 and the plasma reactor 5 are interposed in the middle of the first exhaust pipe 31.

[0031] The second exhaust pipe 32 is a pipe for discharging exhaust gas, bypassing the adsorption member 4 and the plasma reactor 5. The second exhaust pipe 32 has an upstream end 32A and a downstream end 32B in the direction of exhaust gas flow. The upstream end 32A is connected to the first exhaust pipe 31 between the adsorption member 4 and the catalytic converter 2. The downstream end 32B is connected to the first exhaust pipe 31 on the opposite side of the catalytic converter 2 from the plasma reactor 5. The pressure loss when the exhaust gas passes through the second exhaust pipe 32 is smaller than the pressure loss when the exhaust gas passes through the first exhaust pipe 31. Preferably, there are no interposed members in the middle of the second exhaust pipe 32. Preferably, the second exhaust pipe 32 is positioned below the first exhaust pipe 31. By positioning the second exhaust pipe 32 below the first exhaust pipe 31, the adsorption member 4 and the plasma reactor 5 in the first exhaust pipe 31 can be protected from water and other substances discharged from the engine 101.

[0032] (3) Adsorption member The adsorption member 4 is interposed in the middle of the first exhaust pipe 31. The adsorption member 4 is positioned downstream of the catalytic converter 2 in the direction of exhaust gas flow. The adsorption member 4 is positioned between the catalytic converter 2 and the plasma reactor 5 in the direction of exhaust gas flow. The adsorption member 4 is capable of adsorbing hydrocarbons in the exhaust gas.

[0033] More specifically, the adsorption member 4 has a cylindrical shape. The adsorption member 4 extends in the direction in which the first exhaust pipe 31 extends. The adsorption member 4 has a carrier and an adsorption layer inside. The carrier extends in the direction in which the adsorption member 4 extends. The carrier supports the adsorption layer. The carrier is mesh-like or honeycomb-like and has multiple holes through which the exhaust gas passes. The adsorption layer covers the inner surface of the holes in the carrier. The adsorption layer is made of, for example, zeolite. When the exhaust gas passes through the holes in the carrier, the adsorption layer adsorbs hydrocarbons in the exhaust gas.

[0034] (4) Plasma reactor The plasma reactor 5 is interposed in the middle of the first exhaust pipe 31. The plasma reactor 5 is positioned downstream of the adsorption member 4 in the direction of exhaust gas flow. The plasma reactor 5 decomposes harmful components contained in the exhaust gas that has passed through the adsorption member 4. The plasma reactor 5 is a dielectric barrier discharge type plasma reactor.

[0035] More specifically, the plasma reactor 5 has multiple electrode panels 51. The multiple electrode panels 51 are arranged at intervals from each other in a direction perpendicular to the direction in which the first exhaust pipe 31 extends. Each electrode panel 51 extends in the direction in which the first exhaust pipe 31 extends. Each electrode panel 51 has a flat plate shape. The exhaust gas passes between each electrode panel 51.

[0036] Each electrode panel 51 has a conductive layer and a dielectric layer covering the conductive layer. The conductive layer is made of a metal (conductor), such as tungsten. The dielectric layer is made of a ceramic (dielectric), such as aluminum oxide.

[0037] When power is supplied to each electrode panel 51, a discharge (dielectric barrier discharge) occurs between each electrode panel 51. This causes the gas between each electrode panel 51 to become a plasma state. In other words, plasma is generated inside the plasma reactor 5. Then, harmful components contained in the exhaust gas are decomposed by the plasma. The exhaust gas that has passed through the plasma reactor 5 passes through the exhaust pipe 3 and is discharged outside the vehicle.

[0038] (5) Valve Valve 6 adjusts the balance between the amount of exhaust gas passing through the first exhaust pipe 31 and the amount of exhaust gas passing through the second exhaust pipe 32. Valve 6 is located at the connection point between the downstream end 32B of the second exhaust pipe 32 and the first exhaust pipe 31. The position of valve 6 is not limited. For example, valve 6 may be located at the connection point between the upstream end 32A of the second exhaust pipe 32 and the first exhaust pipe 31. Also, valve 6 may be provided in both the first exhaust pipe 31 and the second exhaust pipe 32. Valve 6 is an electromagnetic valve.

[0039] In the following explanation, when referring to the opening degree of valve 6, the opening degree on the first exhaust pipe 31 side is used as the reference. For example, when the opening degree of valve 6 is 100%, all of the exhaust gas passes through the first exhaust pipe 31. When the opening degree of valve 6 is 100%, the exhaust gas does not pass through the second exhaust pipe 32. When the opening degree of valve 6 is 0%, all of the exhaust gas passes through the second exhaust pipe 32. When the opening degree of valve 6 is 0%, the exhaust gas does not pass through the first exhaust pipe 31.

[0040] (4)Power supply device The power supply unit 7 can supply power from the battery 102 to each electrode panel 51 of the plasma reactor 5. The power supply unit 7 is electrically connected to the battery 102. The power supply unit 7 is also electrically connected to each electrode panel 51. The power supply unit 7 can be switched on or off. When the power supply unit 7 is on, it can supply power to the electrode panels 51. When the power supply unit 7 is off, it does not supply power to the electrode panels 51.

[0041] (5) Control device The control unit 8 is an ECU (Electronic Control Unit) that performs electrical control of the vehicle 100, and includes a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The control unit 8 is electrically connected to the battery 102. The control unit 8 starts up when the ignition switch of the vehicle 100 is turned on and power is supplied from the battery 102.

[0042] The control device 8 is electrically connected to the power supply unit 7. The control device 8 switches the power supply unit 7 to an ON state or an OFF state by sending a predetermined electrical signal to the power supply unit 7. In other words, the control device 8 controls the power supply unit 7. To put it another way, the control device 8 controls the plasma reactor 5 via the power supply unit 7.

[0043] Furthermore, the control device 8 is electrically connected to the valve 6. The control device 8 controls the opening degree of the valve 6.

[0044] Furthermore, the control device 8 is electrically connected to an accelerator pedal (not shown). The control device 8 can receive an electrical signal (accelerator input value) corresponding to the position of the accelerator pedal. The control device 8 is also electrically connected to the first temperature sensor 9, the second temperature sensor 10, and the airflow meter 11.

[0045] (6) Sensor The first temperature sensor 9 is attached to the catalytic converter 2. The first temperature sensor 9 measures the temperature T inside the catalytic converter 2. (S / C) Measure.

[0046] The second temperature sensor 10 is attached to the first exhaust pipe 31. The second temperature sensor 10 detects the temperature T of the adsorption member 4. (U / F) Measure.

[0047] The airflow meter 11 is attached to the first exhaust pipe 31. The airflow meter 11 measures the flow rate of exhaust gas passing through the first exhaust pipe 31.

[0048] 2. Exhaust system control Next, we will explain the control of the exhaust system 1.

[0049] When the ignition switch of vehicle 100 is turned on, the control device 8 is activated. Furthermore, when the starter motor turns, the engine 101 starts. Once the engine 101 starts, exhaust gas from the engine 101 flows into the catalytic converter 2.

[0050] However, immediately after the engine 101 is started, the catalyst in the catalytic converter 2 is not activated and has a low ability to decompose harmful components. As a result, harmful components in the exhaust gas flow into the exhaust pipe 3 without being decomposed by the catalytic converter 2.

[0051] Immediately after the engine 101 is started, the proportion of hydrocarbons in the exhaust gas that has passed through the catalytic converter 2 is, for example, 1 volume percent or more.

[0052] (1) Valve control immediately after engine start As shown in Figure 2, when the engine 101 starts, the control device 8 switches the power supply unit 7 from the off state to the on state (plasma reactor 5: on state) and opens the valve 6 to 100% (S1).

[0053] As a result, all of the exhaust gas passes through the first exhaust pipe 31. Hydrocarbons in the exhaust gas are adsorbed onto the adsorption material 4. Furthermore, the hydrocarbons in the exhaust gas that have passed through the adsorption material 4 are decomposed by the plasma reactor 5. Therefore, hydrocarbon emissions can be suppressed even when the catalyst in the catalytic converter 2 is not activated.

[0054] The proportion of hydrocarbons in the exhaust gas that has passed through the adsorption member 4 and the plasma reactor 5 is, for example, 0.5 volume percent or less. Even immediately after engine startup, when the catalytic converter 2 is not yet activated, the proportion of hydrocarbons in the exhaust gas can be halved by the adsorption member 4 and the plasma reactor 5.

[0055] Next, the control device 8 controls the temperature T inside the catalytic converter 2. (S / C) If the temperature T1 is less than the first temperature (S2:NO), the valve 6 is kept open to 100% (S1). In other words, the control device 8 controls the temperature T1 in the catalytic converter 2. (S / C) If the temperature is less than the first temperature T1 (S2:NO), the valve 6 is controlled so that all of the exhaust gas passes through the first exhaust pipe 31.

[0056] The first temperature T1 is the temperature at which the catalyst in the catalytic converter 2 is activated. The first temperature T1 is, for example, 300°C.

[0057] Temperature T inside catalytic converter 2 (S / C) When the temperature is below the first temperature T1, the entire exhaust gas is allowed to flow into the first exhaust pipe 31, allowing the adsorption member 4 and the plasma reactor 5 to process hydrocarbons until the catalyst in the catalytic converter 2 is activated. This suppresses the emission of hydrocarbons until the catalyst in the catalytic converter 2 is activated.

[0058] (2) First valve control Next, the control device 8 controls the temperature T inside the catalytic converter 2. (S / C) If the temperature reaches or exceeds the first temperature T1 (S2:YES), the first valve control is executed (S3).

[0059] In the first valve control (S3), the control device 8 controls the valve 6 so that the amount of exhaust gas flowing into the first exhaust pipe 31 is less than or equal to a first predetermined amount. In other words, in the first valve control (S3), the control device 8 adjusts the opening degree of the valve 6 so that the amount of exhaust gas flowing into the first exhaust pipe 31 is less than or equal to a first predetermined amount. Any exhaust gas exceeding the first predetermined amount flows into the second exhaust pipe 32.

[0060] The first specified amount is, for example, 5 g / second.

[0061] When the temperature T of the adsorption member 4 (U / F) is less than the second temperature T2 (S4: NO), the first valve control is continued (S3). That is, when the temperature T in the catalytic converter 2 (S / C) is equal to or higher than the first temperature T1 (S2: YES) and the temperature T of the adsorption member 4 (U / F) is less than the second temperature T2 (S4: NO), the valve 6 is controlled so that the amount of exhaust gas passing through the first exhaust pipe 31 becomes not more than the first specified amount (S3).

[0062] The second temperature is the temperature at which hydrocarbons are desorbed from the adsorption member 4. The second temperature T2 is, for example, 300°C.

[0063] When the temperature T in the catalytic converter 2 (S / C) becomes equal to or higher than the first temperature T1, the catalyst in the catalytic converter 2 is activated. Therefore, the hydrocarbons in the exhaust gas can be decomposed by the catalyst in the catalytic converter 2.

[0064] Therefore, when the temperature T in the catalytic converter 2 (S / C) is equal to or higher than the first temperature T1, the exhaust gas passing through the catalytic converter 2 contains almost no hydrocarbons. When the temperature T in the catalytic converter 2 (S / C) is equal to or higher than the first temperature T1, the proportion of hydrocarbons in the exhaust gas passing through the catalytic converter 2 is, for example, 0.01% by volume or less.

[0065] Therefore, in the first valve control (S3), the opening degree of the valve 6 is adjusted so that not more than the first specified amount of the exhaust gas passing through the catalytic converter 2 flows through the first exhaust pipe 31, and the amount exceeding the first specified amount flows through the second exhaust pipe 32.

[0066] Thereby, while increasing the temperature of the adsorption member 4, the exhaust gas can be efficiently discharged to the outside of the vehicle using the second exhaust pipe 32 having a lower pressure loss than the first exhaust pipe 31.

[0067] (3) Second valve control Next, the control device 8 controls the temperature T of the adsorption member 4. (U / F) If the temperature reaches or exceeds the second temperature T2 (S4:YES), the second valve control is executed (S5).

[0068] Temperature T of adsorption member 4 (U / F) If the temperature is above the second temperature T2, the hydrocarbons adsorbed on the adsorption member 4 are desorbed from the adsorption member 4. The hydrocarbons desorbed from the adsorption member 4 are decomposed by the plasma reactor 5.

[0069] In the second valve control (S5), the control device 8 controls valve 6 so that the amount of exhaust gas flowing into the first exhaust pipe 31 is less than or equal to a second predetermined amount. In other words, in the second valve control (S5), the control device 8 adjusts the opening of valve 6 so that the amount of exhaust gas flowing into the first exhaust pipe 31 is less than or equal to a second predetermined amount. Any exhaust gas exceeding the second predetermined amount flows into the second exhaust pipe 32.

[0070] The second predetermined amount is greater than the first predetermined amount. The second predetermined amount is set within a range in which the hydrocarbons desorbed from the adsorption member 4 can be decomposed by the plasma reactor 5. The second predetermined amount is, for example, 20 g / second.

[0071] Temperature T of adsorption member 4 (U / F) When the temperature reaches a second temperature T2 or higher, increasing the amount of exhaust gas flowing into the first exhaust pipe 31 allows for efficient desorption of hydrocarbons adsorbed on the adsorption member 4.

[0072] The control device 8 continues to control the second valve until a predetermined time has elapsed since the start of second valve control (S6:NO) (S5).

[0073] The predetermined time is set so that almost all of the hydrocarbons adsorbed on the adsorption member 4 can be desorbed. The predetermined time is, for example, 10 minutes.

[0074] (4) End of valve control If a predetermined time has elapsed since the start of second valve control (S6: YES), the control device 8 sets the valve opening to 0% (S7) and terminates valve control. The control device 8 also switches the power supply unit 7 from the ON state to the OFF state (plasma reactor 5: OFF state).

[0075] Once valve control is complete, all of the exhaust gas that has passed through the catalytic converter 2 is discharged outside the vehicle through the second exhaust pipe 32.

[0076] 3. Effects (1) As shown in Figure 1, according to the exhaust system 1, until the catalyst in the catalytic converter 2 is activated, the exhaust gas that has passed through the catalytic converter 2 is passed through the first exhaust pipe 31, and hydrocarbons in the exhaust gas can be treated by the adsorption member 4 and the plasma reactor 5.

[0077] At this time, the exhaust gas from the engine 101 passes through the catalytic converter 2, the adsorption member 4, and the plasma reactor 5 in that order.

[0078] Therefore, the temperature of the catalytic converter 2 can be raised faster than that of the adsorption member 4. As a result, the catalyst in the catalytic converter 2 can be activated before the hydrocarbons adsorbed on the adsorption member 4 are desorbed from the adsorption member 4.

[0079] After the catalyst in the catalytic converter 2 is activated, hydrocarbons in the exhaust gas can be processed by the catalytic converter 2, while hydrocarbons desorbed from the adsorption member 4 can be processed by the plasma reactor 5.

[0080] As a result, hydrocarbon emissions immediately after engine startup can be reduced.

[0081] (2) As shown in Figure 2, according to the exhaust system 1, the control device 8 controls the temperature T in the catalytic converter 2. (S / C)If the first temperature T1 is less than (S2:NO), the valve 6 is controlled so that all of the exhaust gas passes through the first exhaust pipe 31. The first temperature T1 is the temperature at which the catalyst in the catalytic converter 2 is activated.

[0082] This allows hydrocarbons to be processed by the adsorption member 4 and the plasma reactor 5 until the catalyst in the catalytic converter 2 is activated.

[0083] As a result, hydrocarbon emissions can be suppressed until the catalyst in catalytic converter 2 is activated.

[0084] (3) As shown in Figure 2, according to the exhaust system 1, the control device 8 controls the temperature T in the catalytic converter 2. (S / C) The temperature of the adsorption member 4 is above the first temperature T1 (S2: YES), and the temperature of the adsorption member 4 is T (U / F) If the second temperature T2 is less than (S4:NO), the valve 6 is controlled so that the amount of exhaust gas passing through the first exhaust pipe 31 is less than or equal to a first predetermined amount (S3). The second temperature T2 is the temperature at which hydrocarbons are desorbed from the adsorption member 4.

[0085] Temperature T inside catalytic converter 2 (S / C) When the temperature rises above the first temperature T1, the catalyst in the catalytic converter 2 is activated. As a result, the catalyst in the catalytic converter 2 can decompose hydrocarbons in the exhaust gas.

[0086] Therefore, the valve 6 is controlled to allow the exhaust gas that has passed through the catalytic converter 2 to flow to the first exhaust pipe 31 if it is below a first predetermined amount, and to flow to the second exhaust pipe 32 if it exceeds the first predetermined amount.

[0087] This allows the temperature of the adsorption member 4 to be increased while the exhaust gas can be efficiently discharged outside the vehicle using the second exhaust pipe 32, which has a lower pressure loss than the first exhaust pipe 31.

[0088] 4. Variations (1) In determining whether or not to start the first valve control (S3) (S2), the control device 8 may use the integrated value of the exhaust gas flow rate and the air-fuel ratio.

[0089] (2) In the first valve control (S3), the opening degree of the valve 6 may be controlled based on the amount of exhaust gas discharged from the engine 101. The amount of exhaust gas discharged from the engine 101 may be calculated, for example, from the intake air amount. In this case, if the amount of exhaust gas discharged from the engine 101 is less than or equal to a first predetermined amount, the valve opening degree may be controlled to 100%, and if the amount of exhaust gas discharged from the engine 101 exceeds the first predetermined amount, the valve opening degree may be controlled to 0%.

[0090] (3) In determining whether or not to start the second valve control (S5) (S4), the control device 8 may use the integrated value of the exhaust gas flow rate and the air-fuel ratio.

[0091] (4) In determining whether or not to terminate valve control (S6), the control device 8 may use the temperature of the adsorption member 4 and the operating conditions of the engine 101. [Explanation of symbols]

[0092] 1. Exhaust System 2. Catalytic converter 3 Exhaust pipe 4. Adsorption Member 5 Plasma Reactor 6 valves 8 Control device 31. First exhaust pipe 32. Second exhaust pipe 101 Engine

Claims

1. A catalytic converter connected to the engine, An exhaust pipe connected downstream of the catalytic converter, comprising an exhaust pipe that branches into a first exhaust pipe and a second exhaust pipe midway, A plasma reactor interposed in the middle of the first exhaust pipe, Interposed in the middle of the first exhaust pipe and positioned between the catalytic converter and the plasma reactor, an adsorption member capable of adsorbing hydrocarbons in the exhaust gas, A valve for adjusting the balance between the amount of exhaust gas passing through the first exhaust pipe and the amount of exhaust gas passing through the second exhaust pipe. Equipped with, The second exhaust pipe has an upstream end and a downstream end in the direction in which the exhaust gas flows. The upstream end is connected to the first exhaust pipe between the adsorption member and the catalytic converter. The downstream end is connected to the first exhaust pipe on the opposite side of the catalytic converter from the plasma reactor, forming an exhaust system.

2. Further equipped with a control device, The control device is The exhaust system according to claim 1, wherein if the temperature inside the catalytic converter is below a first temperature which is the temperature at which the catalyst inside the catalytic converter is activated, the valve is controlled so that all of the exhaust gas passes through the first exhaust pipe.

3. The control device is The exhaust system according to claim 2, wherein, when the temperature inside the catalytic converter is equal to or greater than the first temperature, and the temperature of the adsorbent is less than the second temperature at which hydrocarbons are desorbed from the adsorbent, the valve is controlled so that the amount of exhaust gas passing through the first exhaust pipe is less than or equal to a predetermined amount.

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